Certain network communication systems utilize network packets for network communications. It is often desirable to monitor network traffic associated with these packet-based networks. To meet these monitoring needs, copies of network packets can be forwarded to diagnostic network monitoring tools. Packets are often forwarded using network hubs, test access ports (TAPs), and/or switched port analyzer (SPAN) ports available on network switch systems. For example, certain network switch systems produced by Cisco Systems include SPAN ports to which traffic on the switches is mirrored. Other techniques can also be used to extract copies of network packets being communicated within a network packet communication system.
When packets pass through one or more network devices within network infrastructure, packets will experience delay associated with their communication path. Network latency is a representation of this packet delay. One problem with current packet network communication systems is that latency has increased due to exponential growth in demand for network communication bandwidth as compared to actual bandwidth that is available within the system. It is often desirable, therefore, to measure latency within a network communication system. One technique to measure network latency due to packet delays caused by network infrastructure is to add timestamps to the packets as they traverse various points in network. However, this direct-timestamp method is intrusive and can itself add latency to existing packets streams by increasing the amount of data being communicated. Another technique to measure latency due to packet delay is to send special timing packets (e.g., pings) and to measure delay associated with special timing response packets through timestamps added to the timing packets and the timing response packets. PTP (Precision Time Protocol) and NTP (Network Time Protocol) are communication protocols that use such special timing packets. These timing-packet techniques, however, are also intrusive and can adversely affect network bandwidth because the number of packets being communicated within the network are increased.